Guppy care, simplified
Complete Guppy Care Guide
Healthy guppies come from five things done consistently: a cycled tank, stable water, modest feeding, peaceful tank mates and a maintenance routine you can repeat. This guide gives you the numbers, the routine and the next step for each.
- 20–28°C68–82°F
- pH 7.0–8.0GH 8–18°dH
- 0 ppmammonia & nitrite
- 25% weeklywater change
Care basics
Four habits make guppy care much easier
Guppies are adaptable, but a colorful, active fish still depends on a stable environment. Get the biological foundation right first; everything else becomes easier to judge.
Cycle before stocking
Clear water is not a mature aquarium. Establish the biological filter so it can process waste before the full group arrives.
Favor stability
Steady temperature and chemistry matter more than chasing a perfect number with quick corrections.
Feed modestly
Quality food, small portions and the fish’s real appetite. Excess food becomes a water-quality problem fast.
Observe every day
Changes in breathing, posture, appetite or swimming often show a problem before the tank looks wrong.
Care sheet
Guppy care sheet at a glance
| Factor | Target | What it means in practice |
|---|---|---|
| Temperature | 20–28°C (68–82°F) | Pick one stable temperature that suits your fish and tank mates. See the temperature guide. |
| pH | 7.0–8.0 | Check your source water and the breeder’s conditions before changing established chemistry. |
| Ammonia / nitrite | 0 ppm | Any detectable reading points to the filter, recent stocking, feeding or maintenance. |
| Hardness | GH 8–18°dH, KH 5–15°dKH | Test hardness as well as pH; do not add salts or buffers blindly. |
| Tank size | 45 L (about 12 US gal) or more for a small group | Plan for adults and fry, not their size on arrival. |
| Water change | About 25% weekly | A starting routine; adjust to test results, stocking and waste buildup. |
| Filtration | Mature biological media | Dependable flow and surface movement without a strong current for long fins. |
Reference ranges from OATA’s guppy and molly care sheet. They are husbandry guidance, not a guarantee for every strain, life stage or aquarium. For more detail, read the guppy water parameters guide.
Tank setup
Build a tank that can handle the real fish load
The biological filter turns ammonia into nitrite and then nitrate. A zero reading in a newly filled tank does not prove it is cycled: the filter has to process an ongoing waste load. Work through the tank cycling checklist before stocking.
- Add fish gradually. Recheck ammonia and nitrite after each addition. Use the 5-gallon, 10-gallon and 20-gallon stocking guides as planning tools, not fixed counts.
- Choose gentle, dependable filtration. Compare a sponge filter with other filter options, and guard intakes if fry are possible.
- Give cover and swimming space. Plants and structure offer security; open water lets active fish swim and feed normally.
- Plan before mixing sexes. Guppies breed readily, so make room for fry, separation or grow-out first.
Next: beginner tank setup · complete setup guide · best live plants
Water & equipment
Use numbers to understand the tank, not to fight it
Test consistently and learn your source water. If a reading changes suddenly, find the cause before adding products. The goal is a stable, biologically healthy aquarium, not a chart-perfect result created by constant correction.
Water quality
Test ammonia, nitrite, nitrate and pH at least weekly in an established tank, and right away when appetite or behavior changes. Check GH/KH too, especially with soft source water or drifting pH.
Filtration & oxygen
Keep the biological filter healthy and the surface moving for gas exchange. Heat, crowding, decaying waste and some treatments all reduce oxygen.
Heater & thermometer
Use a heater when room temperature would fall or swing outside the range, and confirm with a separate thermometer rather than the heater dial.
Feeding & tank mates
Small meals, peaceful companions, room to behave normally
Guppies are active omnivores. Use a quality staple and rotate suitable extras from safe sources. Fry need smaller food and more frequent meals, so their tanks need closer watching.
- Feed what they eat. One or two small meals a day suits most healthy adults. Begging is not a portion guide. See feeding frequency, best food and overfeeding signs.
- Remove leftovers. Uneaten food decays and pushes water quality the wrong way. If the water turns hazy, use the cloudy water guide.
- Choose peaceful tank mates. Avoid fin nippers and fish big enough to eat guppies. Check before adding bettas, neon tetras or shrimp.
- Watch social pressure. Both mixed and male-only groups can chase. Learn male vs female guppies and act when one fish cannot rest or feed.
Next: feeding guide · tank mate guide
Maintenance
A routine you can actually keep
Plan a weekly partial water change instead of waiting for dirt or illness. OATA suggests 25% weekly for guppies and mollies; adjust the amount and timing to test trends, stocking and source water.
Daily
Observe
- Appetite, breathing, posture, swimming
- Filter flow and heater working
- Chasing, hiding or surface gasping
- Remove uneaten food
Weekly
Measure & change
- Test water and log anything unusual
- About 25% partial water change
- Dechlorinate and match temperature
- Top-ups never replace water changes
As needed
Respond
- Rinse filter media if flow drops
- Trim plants, check intake guards
- Review stocking before adding fish
- Investigate sudden parameter shifts
Breeding and fry tanks usually need more frequent maintenance. Use the maintenance schedule and water change frequency guide. An old tank with low pH needs gradual correction, never a sudden jump.
Growth, breeding & behavior
Plan for a growing, changing group
Lifespan & growth
Guppies are a multi-year commitment, and size and lifespan depend on the fish and its care. Read how long guppies live and growth stages.
Breeding & fry
A mixed group breeds without help and females can store sperm. Keep males only to control numbers, or plan space first: how to breed guppies, pregnancy stages, raising fry.
Normal vs warning signs
Healthy guppies are curious, use the upper and middle water and rush to feed. Watch for hiding, not eating, glass surfing or bullying.
Arrival & health
Prepare before delivery, check the environment first
Read the arrival instructions before the box comes, so you are not deciding while fish are under transport stress. When a fish looks unwell, test the water before reaching for treatments.
Prepare a mature tank. Verify filtration, temperature, water and capacity before delivery.
Set up observation. A separate filtered tank for quarantine, and log the first week.
Follow the arrival policies. Read the acclimation guide and live arrival / DOA terms before opening the bags.
| What you see | Check first | Read next |
|---|---|---|
| White salt-like spots, flashing | Other skin changes, breathing | Ich |
| Ragged or shrinking fins | Injury, fin nipping, water quality | Fin rot |
| Fins held tight to the body | Water results, aggression | Clamped fins |
| Gasping at the surface | Aeration, filter flow, tests now | Gasping |
| Swollen body, raised scales | Seek prompt help | Dropsy |
| Swollen belly only | Sex, timeline, appetite | Bloated guppy |
| Gold dust on the body | Lighting, other signs | Velvet |
| Cottony patches, mouth lesions | Get lesions assessed | Columnaris |
| Floating, sinking, off balance | Posture, breathing, environment | Swim bladder |
| Thin body, white stringy poop | Feeding and body condition | Internal parasites |
Similar signs can have different causes, and this table is not a diagnosis. For severe, persistent or spreading signs, move the fish to a stable hospital tank and seek an aquatic veterinarian. Full overview: guppy health guide.
Keep reading
Choose your next care guide
Water & feeding
Buying & arrival
FAQ
Common guppy care questions
Do guppies need a heater?
A heater is useful whenever room temperature would fall or swing outside 20–28°C (68–82°F). Check the actual water temperature with a thermometer instead of trusting the heater dial.
How often should I change guppy tank water?
Start with a weekly partial change of about 25%, then adjust to test results, stocking and waste buildup. Test sooner after new fish, equipment problems or unusual behavior. See the water change guide.
Can I keep only male guppies?
Yes. Male-only groups are common and prevent fry, but they still need space, plants and observation because chasing can happen without females.
How many guppies can live in a 10-gallon tank?
There is no responsible single number: adult size, sex ratio, filtration, plants, maintenance and fry all matter. Start conservatively and use the 10-gallon stocking guide.
Why are my guppies producing so many fry?
Guppies are livebearers and females can store sperm, so mixed groups breed repeatedly. Plan grow-out space, separation or rehoming before keeping males and females together.
Should I add aquarium salt to every guppy tank?
No. Salt needs a clear purpose and must suit the plants, tank mates and underlying problem. It is not required for a healthy guppy aquarium.
Build the aquarium first
Prepare the tank, then choose the fish
Match the group to your tank size, experience and receiving plan, not just color or price.
